Wheeled chair with a seat locking unit

ABSTRACT

A wheeled chair includes a wheeled frame having an upright post that defines a vertical axis, a seat mounted rotatably on the upright post so as to be turnable relative to the wheeled frame about the vertical axis, and a seat locking unit including a retaining member secured to the upright post and formed with a plurality of retaining grooves, a mounting seat secured to the seat, and a spring-biased tongue member disposed above the retaining grooves, mounted movably on the mounting seat, and operable so as to be moved between a locking position, in which, the tongue member is moved downwardly to selectively engage one of the retaining grooves so as to prevent turning of the seat relative to the wheeled frame, and an unlocking position, in which, the tongue member is moved upwardly to disengage from the selected one of the retaining grooves so as to permit turning of the seat relative to the wheeled frame.

BACKGROUND OF THE INVENTION

[0001] 1. Field of the invention

[0002] This invention relates to a wheeled chair, more particularly to a wheeled chair with a seat locking unit.

[0003] 2. Description of the related art

[0004] FIGS. 1 to 3 illustrate a conventional wheeled chair which includes a wheeled frame 10 with a cylindrical upright post 11, a seat 22 with an inserting protrusion 221 projecting downwardly into a top recess of the upright post 11 and being turnable relative to the upright post 11, and a seat locking unit 30 mounted on a bottom side 222 of the seat 22. The seat locking unit 30 includes a retaining plate 31 secured to the upright post 11 and formed with a plurality of retaining grooves 311, a lever 34 having one end 341 pivoted to the bottom side 222 of the seat 22 and the other end 342 projecting laterally and outwardly from the bottom side 222 of the seat 22, a tongue 343 projecting from the lever 34 toward the retaining plate 31, and a coil spring 35 having one end secured to the bottom side 222 of the seat 22 and the other end secured to the lever 34 so as to urge the lever 34 to move toward the retaining plate 31. The lever 34 is turnable toward and away from the retaining plate 31 about a vertical axis, which is parallel to the upright post 11, between a locking position (see FIG. 2), in which, the tongue 343 is urged by the coil spring 35 to move toward the retaining plate 31 so as to engage a selected one of the retaining grooves 311, and an unlocking position (see FIG. 3), in which, the tongue 343 moves away from the retaining plate 31 against an urging force of the coil spring 35 so as to disengage from the selected one of the retaining grooves 311 and so as to permit rotation of the seat 22 relative the upright post 11. Two diametrically disposed stoppers 32, 33 project downwardly from the bottom side 222 of the seat 22, and are disposed adjacent to the retaining plate 31. The retaining plate 31 further has a protrusion 312 projecting laterally and outwardly from a peripheral edge thereof so as to selectively engage one of the stoppers 32, 33 (see FIG. 3) when the seat 22 turns relative to the upright post 11.

[0005] The conventional wheeled chair is disadvantageous in that operation of the lever 34 as such is not ergonomical and that a relatively strong coil spring 35 is needed to enhance engagement between the tongue 343 and the selected retaining groove 311. As a consequence, the operation of the lever 34 is relatively laborious. Moreover, disengagement of the tongue 343 from the selected retaining groove 311 is required when the seat 22 is to be separated from the wheeled frame 10, which results in inconvenience during the disassembly operation.

SUMMARY OF THE INVENTION

[0006] Therefore, it is an object of the present invention is to provide a wheeled chair with a seat locking unit that is capable of overcoming the aforementioned drawbacks.

[0007] According to the present invention, a wheeled chair comprises: a wheeled frame having an upright post that has a top end and that defines a vertical axis; a seat disposed over the upright post and having a bottom side, and an inserting protrusion that projects downwardly from the bottom side and that is mounted rotatably on the top end of the upright post so as to permit turning of the seat relative to the wheeled frame about the vertical axis; and a seat locking unit including a retaining member secured to the top end of the upright post and formed with a plurality of retaining grooves which are angularly spaced apart from each other, a mounting seat secured to the bottom side, and a spring-biased tongue member disposed above the retaining grooves, mounted movably on the mounting seat, and operable so as to be moved between a locking position, in which, the tongue member is moved downwardly by an urging force to selectively engage one of the retaining grooves so as to prevent turning of the seat relative to the wheeled frame about the vertical axis, and an unlocking position, in which, the tongue member is moved upwardly to disengage from the selected one of the retaining grooves so as to permit turning of the seat relative to the wheeled frame about the vertical axis.

BRIEF DESCRIPTION OF THE DRAWINGS

[0008] In drawings which illustrate an embodiment of the invention,

[0009]FIG. 1 is a perspective view of a conventional wheeled chair with a seat locking unit;

[0010]FIG. 2 is a fragmentary bottom view of the wheeled chair with the seat locking unit of FIG. 1 at an locking position;

[0011]FIG. 3 is a fragmentary bottom view of the wheeled chair with the seat locking unit of FIG. 1 at a unlocking position;

[0012]FIG. 4 is a perspective view of a wheeled chair with a seat locking unit embodying this invention;

[0013]FIG. 5 is a fragmentary exploded view of the wheeled chair with the seat locking unit of FIG. 4;

[0014]FIG. 6 is an exploded perspective view of the seat locking unit of FIG. 4;

[0015]FIG. 7 is a partly sectional view of the seat locking unit of FIG. 4 at a locking position;

[0016]FIG. 8 is a fragmentary bottom view of the wheeled chair of FIG. 4; and

[0017]FIG. 9 is a partly sectional view of the seat locking unit of FIG. 4 at an unlocking position.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT

[0018] FIGS. 4 to 9 illustrate a wheeled chair embodying this invention. The wheeled chair includes: a wheeled frame 40 having an upright post 41 that has a top end 413 and that defines a vertical axis (X); a seat 52 disposed over the upright post 41 and having a bottom side 523, and an inserting protrusion 522 that projects downwardly from the bottom side 523 and that is mounted rotatably on the top end 413 of the upright post 41 so as to permit turning of the seat 52 relative to the wheeled frame 40 about the vertical axis (X); and a seat locking unit including a retaining member 61 secured to the top end 413 of the upright post 41 and formed with a plurality of retaining grooves 611 which are angularly spaced apart from each other, a mounting seat 62 secured to the bottom side 523, and a spring-biased tongue member 63 disposed above the retaining grooves 611, mounted movably on the mounting seat 62, and operable so as to be moved between a locking position (see FIG. 7), in which, the tongue member 63 is moved downwardly by an urging force to selectively engage one of the retaining grooves 611 so as to prevent turning of the seat 52 relative to the wheeled frame 40 about the vertical axis (X), and an unlocking position (see FIG. 9), in which, the tongue member 63 is moved upwardly to disengage from the selected one of the retaining grooves 611 so as to permit turning of the seat 52 relative to the wheeled frame 40 about the vertical axis (X).

[0019] The upright post 41 is cylindrical in shape and is formed with a cylindrical top recess 412. The inserting protrusion 522 is cylindrical in shape and has a frusto conical bottom end 5221 received in the top recess 412 so as to permit turning of the seat 52 relative to the upright post 41.

[0020] The wheeled chair further includes an operating member that includes a lever 64 which is mounted turnably on the mounting seat 62, which extends in a transverse direction relative to the vertical axis (X) to define a horizontal axis (Y), and which has one end 642 projecting laterally and outwardly from the bottom side 523 of the seat 52, and the other end 641 disposed adjacent to the tongue member 63. The operating member further includes a pushing arm 643 that is transverse to and that extends from the other end 641 of the lever 64 to engage the tongue member 63 so as to lift the tongue member 63 to move upwardly to disengage from the selected one of the retaining grooves 611 when the lever 64 is turned in a direction about the horizontal axis (Y).

[0021] The mounting seat 62 is formed with a tongue receiving space 621 for receiving the tongue member 63, a lever receiving space 622 for receiving fittingly the other end 641 of the lever 64, and an arm receiving space 623 which is transverse to and which is in spatial communication with the lever receiving space 622 and the tongue receiving space 621 and which receives the pushing arm 643. The tongue receiving space 621 has cylindrical upper and lower sections 6211, 6212. The upper section 6211 has a diameter greater than that of the lower section 6212. The tongue member 63 has cylindrical upper and lower portions 632, 633 which are respectively received in the upper and lower sections 6211, 6212 and which cooperately define a neck 634 therebetween. The lower portion 633 of the tongue member 63 extends through the lower section 6212 of the tongue receiving space 621 and into the selected one of the retaining grooves 611 when the tongue member 63 is at the locking position. The upper portion 632 of the tongue member 63 is formed with a top groove 631. The seat locking unit further includes a coil spring 635 that has one end received in the top groove 631, and the other end abutting against the bottom side 523 of the seat 52 so as to urge the tongue member 63 to move downwardly. The pushing arm 643 has a free end that is disposed underneath and that is in contact with the neck 634 so as to lift the tongue member 63 against an urging force of the coil spring 635 when the lever 64 is turned about the horizontal axis (Y).

[0022] The retaining member 61 includes a circular plate that has an upper face 614 and an arcuate stopper 613 projecting upwardly from the upper face 614 and engageable with the mounting seat 62 so as to limit the extent of turning of the mounting seat 62 relative to the upright post 41.

[0023] With the seat locking unit of this invention, the aforementioned drawbacks associated with the prior art can be eliminated.

[0024] With the invention thus explained, it is apparent that various modifications and variations can be made without departing from the spirit of the present invention. It is therefore intended that the invention be limited only as recited in the appended claims. 

I claim:
 1. A wheeled chair comprising: a wheeled frame having an upright post that has a top end and that defines a vertical axis; a seat disposed over said upright post and having a bottom side, and an inserting protrusion that projects downwardly from said bottom side and that is mounted rotatably on said top end of said upright post so as to permit turning of said seat relative to said wheeled frame about said vertical axis; and a seat locking unit including a retaining member secured to said top end of said upright post and formed with a plurality of retaining grooves which are angularly spaced apart from each other, a mounting seat secured to said bottom side, and a spring-biased tongue member disposed above said retaining grooves, mounted movably on said mounting seat, and operable so as to be moved between a locking position, in which, said tongue member is moved downwardly by an urging force to selectively engage one of said retaining grooves so as to prevent turning of said seat relative to said wheeled frame about said vertical axis, and an unlocking position, in which, said tongue member is moved upwardly to disengage from the selected one of said retaining grooves so as to permit turning of said seat relative to said wheeled frame about said vertical axis.
 2. The wheeled chair of claim 1, wherein said upright post is cylindrical in shape and is formed with a cylindrical top recess, said inserting protrusion being cylindrical in shape and having a frusto conical bottom end received in said top recess.
 3. The wheeled chair of claim 1, further comprising an operating member that includes a lever which is mounted turnably on said mounting seat, which extends in a transverse direction relative to said vertical axis to define a horizontal axis, and which has one end projecting laterally from said bottom side of said seat, and the other end disposed adjacent to said tongue member, said operating member further including a pushing arm that is transverse to and that extends from the other end of said lever to engage said tongue member so as to lift said tongue member to move upwardly to disengage from the selected one of said retaining grooves when said lever is turned in a direction about said horizontal axis.
 4. The wheeled chair of claim 3, wherein said mounting seat is formed with a tongue receiving space for receiving said tongue member, a lever receiving space for receiving fittingly the other end of said lever, and an arm receiving space which is transverse to and which is in spatial communication with said lever receiving space and said tongue receiving space and which receives said pushing arm, said tongue receiving space having cylindrical upper and lower sections, said upper section having a diameter greater than that of said lower section, said tongue member having upper and lower portions which are respectively received in said upper and lower sections and which cooperately define a neck therebetween, said lower portion of said tongue member extending through said lower section of said tongue receiving space and into the selected one of said retaining grooves when said tongue member is at said locking position, said upper portion of said tongue member being formed with a top groove, said seat locking unit further including a coil spring that has one end received in said top groove, and the other end abutting against said bottom side of said seat So as to urge said tongue member to move downwardly, said pushing arm having a free end that is disposed underneath and that is in contact with said neck so as to lift said tongue member against the urging force of said coil spring when said lever is turned in said direction about said horizontal axis.
 5. The wheeled chair of claim 4, wherein said retaining member is includes a circular plate that has an upper face and an arcuate stopper projecting upwardly from said upper face and engageable with said mounting seat so as to limit the extent of turning of said mounting seat relative to said upright post. 